Control compass for automatic piloting of moving bodies



Jan. 12, 1937.

w. FRQEEMAN 2,067,441

CONTROL COMPASS FOR AUTOMATIC PILOTING OF MOVING BODIES F iled Jan. 26, 1934 14 Q L 1 l l l fi it 17 I P i 10 /1 16 9 4 T Z j: 7 if V 7 fl [29:1 I 1 INVENTOR ATTORNEY Patented Jan. 12, 1937 UNITED STATES CONTROL COMPASS FOR AUTOMATIC PILOTING OF MOVING BODIES Wood Freeman, Fircrest, Wash.

Application January 26, 1934, Serial No. 708,442

6 Claims. (01. 33-204) The object of my invention is to provide means whereby a magnetic compass may act as a medium for the control of a current in an electric circuit, said current in turn actuating mechanism performing the aforementioned piloting. I attain this object by the devices illustrated in the accompanying drawing, in which,

Figure 1 is a vertical section of a magnetic compass showing control devices in the compass together with a schematic diagram of a connecting electrical circuit and certain novel features contained therein.

Figure 2 is a plan view of the same through a section at Z-Z. Similar numeralsrefer to similar parts throughout the drawing.

The compass bowl I, contains a liquid 2, in which is suspended upon a pivot 5, a magnetic needle '3, said needle being free to swing about said pivot throughout the entire 360 in a plane substantially 90 to the plane of the pivot. The magnetic needle (of which there may be a plurality) carries an electrode 6, at each end, said elethctrodes being electrically connected with each 0 er.

Located on "the inside of the compass bowl,

diametrically opposite each other, and in a plane substantially the same as that generated by the needle in its rotation on the pivot are the electrodes I, which are mounted on the supports 8,

w and are connected with the electrical circuit M,

substantially as shown in Fig. l.

In the lid or top 9, of the compass bowl i, is shown an orifice ill, carrying a valve II, which serves to vent said bowl of excess gases or liquid and through'which liquids or gases may also be admitted to the, bowl.

The liquid 2, is an electrolyte of high resistance being in general distilled water to which has been added a quantity of ethyl alcohol (to prea vent freezing) together with a minute quantity 0! some acid to give sufllcient ions to conduct the required current. The needle 3, should be sheathed in a dielectric covering to prevent corrosion by the current in the electrolyte. The electrodes 8, and I, should be of some material not readily attacked in the electrolysis of the electrolyte. Platinum, carbon, gold or tungsten may be satisfactorily employed.

The electrical circuit M, includes, a source of electrical energy, or current, II, a relay i3, and an interrupter it, all of which are in series with the electrodes, needle and liquid in the compass bowl. The relay i3, is of the sensitive type (operating on about a milliampere) the contacts of 55 whlch'being closed when the armature is released or opened. The contacts oi relay l3 opens and closes circuit R, in which i5, is a source of electrical energy and i6, is a thermionic valve, the plate circuit of which includes a source of electrical energy l1, and a relay l8.

Since the function of the thermionic valve is to take the part of a delayed relay, a magnetic relay with a dash pot dampener might be substituted therefor. Relay i8, operates another circuit (not shown in the drawing) which performs the actual work of steering the vessel.

The mechanism which steers the vessel is also coupled to the bowl of the compass in such a manner that the compass bowl is rotated in the opposite direction from the rudder stock.

The operation of my invention is dependent on the principle of the variable electrical resistance encountered when varying the distance between two electrodes immersed in the'same electrolyte. It appears as though the resistance between two electrodes in the same electrolyte does not vary directly as the distance between the two,

but more nearly as the square of the distance, or some similar function and for that reason when two electrodes approach each other there comes a point where a very slight movement produces a marked eirect in the resistance encountered, and in this case when electrodes 6 and I come near each other a sharp drop in the resistance occurs and a suflicient amount of current will flow in circuit M to close the armature on relay i3, which will open circuit R, causing a cessation of filament current in the thermionic valve, which in turn blocks the plate current in said valve with a consequent opening of relay i8. As said before relay l8 operates another circuit which performs the actual work of steering, the mechanism 01' which operates in either direction depending on whether relay i8, is open or closed.

This mechanism is continuous in its operation with no neutral point or dwell, the operation being as iollows,--

Assume the ship to be on the desired course and the position of the needle, electrodes and relays as shown in the drawing Fig. 1 and Fig. 2. A switch (not shown) is closed which energizes all circuits, immediately the mechanism in the circuit beyond relay ill will function to rotate the compass bowl anticlockwise which will cause electrodes 6-6 and 1-1 to approach each other. A point will be reached where sufilcient current will flow to cause relay l3 to close its armature, which opens circuit R, and, as hereinbefore set forth, will open relay i8, which in turn will cause the some means of decreasing the current to a minimum as quickly as possible. To do this I have made use of the novel feature of interrupting the current in circuit M, at regular intervals. The period of interruption being about one-sixtieth of a second and the contact period being about one half second.

Consider that the bowl is being rotated clockwise, and the interrupter II, is periodically breaking the circuit M, allowing the armature in relay it, to open and momentarily close circuit R. If electrodes 8 and I are as close together as they were when relay l3, first closed, relay It, will close again when interrupter it closes circuit M. If, however, electrodes 6 and l are farther apart than they were when relay l3, first closed, relay i3 will 'remain open, when interrupter ll, again closes circuit M, and circuit R, will be closed a sumcient length of time to heat the filament of the thermionic valve with the results as before described.

Suppose now that something has suddenly caused the vessel to veer to starboard. Electrodes i and 1 will have been separated farther than the normal back and forth motion and so the mechanism will be set in motion to close the gap between the said electrodes and in so doing will impart a clockwise motion to the rudder stock until such time as electrodes 6 and I have approached each other sufllcient for relay is to close. The helm is now starboard, the vessel is turning to port, the direction thereby imparted to the compass bowl being anticlockwise, causing electrodes 6 and l to approach still closer together, but with relay ll being closed circuit R is opened which in turn opens relay It, thereby reversing direction of the steering mechanism, and rotation of the compass bowl, separating electrodes I and I, up to the critical reversing point again. This operation is repeated and each time the compass bowl makes a slight advance in the clockwise direction, and the rudder likewise is brought to the position of corresponding advance until such time as the vessel has returned to its original course.

When the vessel is on the selected course, the rudder and compass bowl being intimately connected, gyrate through very small arcs simultaneously, but with opposite angular direction.

Direct current may be satisfactorily employed in this device since any gases which are formed may readily escape through the orifice ill, in the lid. Also since the needle carries the conductor,

(said conductor being either integral with or securely fastened thereto) there is no appreciable eii'ect by the very minute current employed on the directional qualities of the needle. Alternating current may also be used without difl'lculty so long as the relay in circuit M is of the type suitable for operating with alternating current.

The bowl of the compass, or casing, should be of some material having dielectric qualities such that it will not be readily attacked by electrolysis. Glass. rubber, bakeiite and such are satisfactory. Various changes may be made in the forms,

and details of the device without departing from the spirit of my invention since I do not consider myself limited to the precise details shown in the drawing, but am entitled to all the variations thereof as may fall within the scope of the claims.

I am aware that previously inventions have been made wherein electric current is conducted through a compass bowl using an electrolytic medium and that such devices have been employed for operating electrical circuits, which in turn operated mechanisms for steering vessels. I therefore do not claim such combinations broad- 1y; but I claim:

1. In combination, a magnetic compass having a'casing bearing opposed electrodes, a magnetic needle pivoted in said casing positioned so that its ends approach, but do not contact, the respective electrodes, as the course of the carrying craft changes, an electric circuit including said needle, 9. source of current, an interrupter and a relay, all in series, and an electrolytic liquid in said casing in which said electrodes and needle are im mersed, for completing said circuit.

2. In combination, a magnetic compass having a casing bearing opposed electrodes, a magnetic needle pivoted in said casing positioned so that its ends approach, but do not contact, the respective electrodes, as the course of the carrying craft changes, an electric circuit including said needle, a source of current, an interrupter and a relay, all in series, and an electrolytic liquid in said casing [in which said electrodes and needle are immersed,

for completing said circuit, a second electrical circuit, including, a source of electrical energy and a relay in series with the contacts of the said relay in'the first described electrical circuit, said relay in said second circuit includng means for momentarily delaying the closing of a third electrical circuit, said third electrical circuit, including a source of electrical energy, and a relay both of which are electrically connected in series with the delayed relay of the said second circuit.

3. In combination, a magnetic compass having a casing bearing opposed electrodes, a magnetic needle pivoted in said casing, positioned so that its ends approach but do not contact the respective electrodes, asthe course of the carrying craft changes, an electric circuit including said needle, a source of current, an interrupter and a relay, all in series, and an electrolytic liquid in said casing in which said electrodes and needle are immersed for completing said circuit, a second electric circuit including a source of electric current and a relay in series with the contacts of the relay in the first described circuit, said relay in said second circuit having means for delaying the closing of a third electric circuit when the contacts of the relay in the first described electric circuit are brought together.

4. In combination, a magnetic compass having a casing bearing opposed electrodes, a magnetic needle pivoted in said casing. positioned so that its ends approach but do not contact the respective electrodes, as the course of the carrying craft changes, an electrical circuit including said needle, a source of current, an interrupter and a relay all in series, and an electrolytic liquid in said casing in which said electrodes and needle are immersed for completing said circuit, a second electric circuit including a source of electric current and a thermionic valve whose filament is in series with said second circuit, said second circuit being completed through'the contacts of said relay, said thermionic valve having a plate circuit, including a source of current ands sewnd relay in series with said plate.

5. In combination. a magnetic compass having acaslngofdielectricmateriahbearing iw led circuit including said electrical conductor, a

electrodes, a dielectric covered magnetic needle carrying an electrical conductor, said electrical conductor having at each of its ends an electrode, said magnetic needle pivoted in said casing positioned so that the electrodes on the ends of the electrical conductor approach, but do not contact the respective electrodes on the casing, as the course of the carrying craft changes, an electrical source 01' current, an interrupter and a relay all in series, and an electrolytic liquid in said casing in which said electrodes, the dielectric covered needle, and the electrical conductor with its electrodes are immersed, for completing said circuit.

6. In combination, a magnetic compass having a rotatable casing bearing opposed electrodes, a magnetic needle pivoted insaid casing, positioned so that its ends approach but do not contact the respective electrodes as the casing is rotated, an electric circuit including said needle, a source 0! current. an interrupter and a relay, all in series, and an electrolytic liquid in said casing, in which said electrodes and needle are immersed for completing said circuit, a second electric circuit controlled by the relay in the first circuit, said second circuit including a source or current in series with the filament of a thermionic valve, said thermionic valve having a plate circuit, including a source or current and a relay in series with said plate, said relay in said plate circuit controlling the direction of operation of a continuously operatlng mechanism, said mechanism heing coupled to, and in such a manner so as, to cause rotation or the aforesaid rotatable casing, said mechanism operating in the one direction or the other,

without any neutral point or dwell, depending on whether the relay in said plate circuit is open or closed.

WOOD FREEMAN. 20 

